Question

Database server is Microsoft SQL Server, but I don’t have Administrator access to it.
So, I don’t know which version, and I don’t know which indexes exist.

To access the database, I am using ADO.

Here is the SQL statement:

-- Get master objid and order_number and activity time
SELECT A.objid,
       A.order_number,
       F.entry_time
-- From these tables
FROM   dbo.table_master as A,
       dbo.table_activity as F
-- link of the tables
WHERE  F.objid = A.objid
       -- Retrieve code = 1900 only
       AND F.code = 1900
       -- Which have info like this:
       AND F.info LIKE '%to SUPPORT.'
       -- And entry time between these times:
       AND F.entry_time >= '2011-10-01 00:00:00'
       AND F.entry_time <= '2011-12-05 23:59:59'
-- We want the earliest entry (because there might be multiple code = 900 and info like)
ORDER  by F.entry_time  

Is it possible to optimize this?

Thanks

Answer 1

Here are things you could do differently:

• use RIGHT(f.info, 11) = 'to SUPPORT.' instead of F.info LIKE '%to SUPPORT.'
• use an INNER JOIN as @xQbert suggested
• use BETWEEN for the date range instead of the combination of < and >.

In my testing, the only one that made a difference in performance was the first option. All 3 items will generate the same execution plan, however, the RIGHT function was around 10x quicker in my test in terms of actual execution time. I’m using STATISTICS TIME to test.

If possible, I would try to get access to look at the indexes. Having the tables properly indexed will make a way bigger difference than the RIGHT function.